Sunday, July 16, 2017

Validating materials and lights in Stingray

Stingray 1.9 is just around the corner and with it will come our new physical lights. I wanted to write a little bit about the validation process that we went through to increase our confidence in the behaviour of our materials and lights.

Early on we were quite set on building a small controlled "light room" similar to what the Fox Engine team presented at GDC as a validation process. But while this seemed like a fantastic way to confirm the entire pipeline is giving plausible results, it felt like identifying the source of discontinuities when comparing photographs vs renders might involve a lot of guess work. So we decided to delay the validation process through a controlled light room and started thinking about comparing our results with a high quality offline renderer. Since SolidAngle joined Autodesk last year and that we had access to an Arnold license server it seemed like a good candidate. Note that the Arnold SDK is extremely easy to use and can be downloaded for free. If you don't have a license you still have access to all the features and the only limitation is that the rendered frames are watermarked.

We started writing a Stingray plugin that supported simple scene reflection into Arnold. We also implemented a custom Arnold Output Driver which allowed us to forward Arnold's linear data directly into the Stingray viewport where they would be gamma corrected and tonemapped by Stingray (minimizing as many potential sources of error).

Material parameters mapping

The trickiest part of the process was to find an Arnold material which we could use to validate. When we started this work we used Arnold 4.3 and realized early that the Arnold's Standard shader didn't map very well to the Metallic/Roughness model. We had more luck using the alSurface shader with the following mapping:

Halfway through the validation process Arnold 5.0 got released and with it came the new Standard Surface shader which is based on a Metalness/Roughness workflow. This allowed for a much simpler mapping:

Investigating material differences

The first thing we noticed is an excess in reflection intensity for reflections with large incident angles. Arnold supports Light Path Expressions which made it very easy to compare and identify the term causing the differences. In this particular case we quickly identified that we had an energy conservation problem. Specifically the contribution from the Fresnel reflections was not removed from the diffuse contribution:

Scenes with a lot of smooth reflective surfaces demonstrates the impact of this issue noticeably:

Another source of differences and confusion came from the tint of the Fresnel term for metallic surfaces. Different shaders I investigaed had different behaviors. Some tinted the Fresnel term with the base color while some others didn't:

It wasn't clear to me how Fresnel's law of reflection applied to metals. I asked on Twitter what peoples thoughts were on this and got this simple and elegant claim made by Brooke Hodgman: "Metalic reflections are coloured because their Fresnel is wavelength varying, but Fresnel still goes to 1 at 90deg for every wavelength". This convinced me instantly that indeed the correct thing to do was to use an un-tinted Fresnel contribution regardless of the metallicness of the material. I later found this graph which also confirmed this:

For the Fresnel term we use a pre filtered Fresnel offset stored in a 2d lut (as proposed by Brian Karis in Real Shading in Unreal Engine 4). While results can diverge slightly from Arnold's Standard Surface Shader (see "the effect of metalness" from Zap Anderson's Physical Material Whitepaper), in most cases we get an edge tint that is pretty close:

Investigating light differences

With the brdf validated we could start looking into validating our physical lights. Stingray currently supports point, spot, and directional lights (with more to come). The main problem we discovered with our lights is that the attenuation function we use is a bit awkward. Specifically we attenuate by I/(d+1)^2 as opposed to I/d^2 (Where 'I' is the intensity of the light source and 'd' is the distance to the light source from the shaded point). The main reason behind this decision is to manage the overflow that could occur in the light accumulation buffer. Adding the +1 effectively clamps the maximum value intensity of the light as the intensity set for that light itself i.e. as 'd' approaches zero 'I' approaches the intensity set for that light (as opposed to infinity). Unfortunatly this decision also means we can't get physically correct light falloffs in a scene:

Even if we scale the intensity of the light to match the intensity for a certain distance (say 1m) we still have a different falloff curve than the physically correct attenuation. It's not too bad in a game context, but in the architectural world this is a bigger issue:

This issue will be fixed in Stingray 1.10. Using I/(d+e)^2 (where 'e' is 1/max_value along) with an EV shift up and down while writing and reading from the accumulation buffer as described by Nathan Reed is a good step forward.

Finally we were also able to validate our ies profile parser/shader and our color temperatures behaved as expected:

Results and final thoughts

Integrating a high quality offline renderer like Arnold has proven invaluable in the process of validating our lights in Stingray. A similar validation process could be applicable to many other aspects of our rendering pipeline (antialiasing, refractive materials, fur, hair, post-effects, volumetrics, ect)

I also think that it can be a very powerful tool for content creators to build intuition on the impact of indirect lighting in a particular scene. For example in a simple level like this, adding a diffuse plane dramatically changes the lighting on the Buddha statue:

The next step is now to compare our results with photographs gathered from a controlled environments. To be continued...

174 comments:

Very cool, i also do some compare between engine and offline renderer, but not integration the renderer in engine, and just compare the final result, i learned a lot, thanks.about the energy conservation, the spcular_scale_bias.y is what?Thanks.

Hi there, spcular_scale_bias.y is the fresnel term stored in the pre calculated lookup (as described here: http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_slides.pdf) Cheers!

Norton.com/Setup is best antivirus available in the market. If you want to protect your system online or locally from any unforeseen events Norton is is a must have software in your PC or Mac. Activate your Norton.com/Setup to protect yourself ad your data from your system from malware and antivirus. Browse internet without any hesitation norton will take care of all malicious antiviruses floating all over internet.

For any concern and help just visit website for Office.com/Setup help and key activation. You can do it by yourself if you know how to install office.com/Setup on your PC or Mac or you can call third party companies as well who can do it on your behalf.

McAfee.com/Activate is a antivirus software for laptop, PC, Mac for internet security form viruses and malware. Enter code to get started and protect while online surfing and downloading.

Since the world is developing each day with new computerized advances, digital dangers, malware, information, and harming diseases have additionally turned out to be increasingly more progressed with every day. These digital contamination harm a gadget or documents in different ways get McAfee.com/Activate

This seems to be very interesting. Quickbooks help you to solve your accounting solution easily. you can put your Qork on Quickbooks easily. if you are facing any issue with Quickbooks then you can contact Quickbooks Payroll Support Number for help.

Brother Printers is a worldwide and dependable brand as far as PC related items. This is a Japanese brand and serving their clients with their best class items for a long time. There are assortments of electronic items which are served to clients. Brother Printers increased tremendous notoriety in the recent years because of their minimal effort items. The propelled PC related items from Brother Printer are spending plan amicable with magnificent administrationsVisit for more :- brother printer service phone number

Very interesting and informative article,i m appreciating your work,keep sharing more.if you have any queries related to your hardware devices like more mobiles, laptop then easily contact our page Geek squad support we provide the best solution for our customer.visit Geek squad tech support

Our particular Python Training bundle planned so that makes us separate from other training focuses and causes our very own strength with the goal that anybody to can learn it and become the stickler of improvement as far as.

Geek Squad Support is a device repair provider that is available globally. The experts at repair desk are efficient and are well trained in dealing with any of customer technical issue. Call the Geek Squad Support specialists at their troubleshoot number, anytime you require, and they will assure some of the great, urgent technical help.

If you don't know about how to reset Arlo login? Dial our toll-free number 1-844-456-4180 for getting all information on Arlo login setup Ip. We will help you related Setup Arlo login.https://arlologin-page.com/

We have a Support Service team for Quickbooks. Need instant solution of your Quickbooks Accounting related. Instantly Dial Quickbooks Support Phone Number for USA user only. Call us on +1-800-901-6679.

Hey! Lovely post. I am a big fan of your work. I really like your website. Undoubtedly QuickBooks is one of the most appealing accounting software. You can easily use and install this software for your business. You can even get best technical help at QuickBooks Customer Service 1-800-329-0391.

Once you connect your laptop to the web, there are lots of websites Associate with it and here the risk arises once you open an unknown link. Over the web, there are viruses; malware and the alternative on-line threat that will transfer in your system if you’re not operating cautiously. Therefore it’s higher and suggested to place an antivirus in your system so you’ll be able to work without fear regarding any on-line threats. We tend to are the third party Norton Antivirus Support supplier within the USA. Our online support team works round the time to grant the most effective at support service to our customers.How to cancel and Refund Norton Subscription 360

Norton product has many powerful tools like norton power eraser which efficently remove all suspecious activityfrom your system and provide you the safe environment to work without worrying about online fraud and viruses.

Are you having issue while completing your marketing assignments? Well, IdealAssignmentHelp will help you with your assignments and help you with the best of experience. Marketing assignment Help experts will not only help you in getting your assignment covered in the given time period also without any kind of mistakes in it. So, get your complex marketing assignment covered without having to stress about the quality anymore. You can also reach out to Essay writing Service experts any time and we will never let you down in terms of quality and as well as rates! Get Connected now for top notch writing experience for excellent future ahead!

I like your content very much. I wanted this only. I have seen it many times, I used to get the answer on your website. Well! let me tell you. I work at china eastern airlines. If you ever want to book tickets in future, Contact us.

Hello, Thanks for sharing the amazing blog. It's very interesting.here are the office setup and installation at https://officesetup.support/.You need to have an Active Office Subscription to download Office on your PC to enjoy all the features. Office is one of the best software that will give you support for all your pen devices as well as flexibility. So, get your office setup office setup

Are you looking for leading Assignment help services provider in Australia? Hire Ideal Assignment Help, our experts will never let you down and make sure that you have an excellent educational life ahead without any kind of stress in between. We are always been one of the most reliable and proficient names in the business.

https://southwestphonenumber.usDial Southwest Phone Number and get best offers for every booking and fly with the cheap rates only with southwest airlines. you can enjoy at your amazing destinations. Our agents are there to help with best solutions over the Southwest Phone Number.

No matter how many times you have made journeys with American Airlines. You still look out for affordable offers and deals for your every journey. For getting the best offers you are often searching a number of times for your tickets. Get impressive deals that are well researched and compared. To get the best fare according to your budget, book your tickets by American Airlines Reservations. Compare the deals with other airlines and choose the right packages which is designed specially for you.

If You are looking for domestic or international flights through american airlines.so you can directly contact at american phone number​​​​​​​ team, and you can reserve their tickets at american airlines reservations. you enjoy your destinations.

If You are looking for domestic or international flights through american airlines.so you can directly contact at american phone number​​​​​​​ team, and you can reserve their tickets at american airlines reservations. you enjoy your destinations.

Your blog provided us with valuable information flight booking deals at your new travel booking partner. Contact our experts. It was the principal airlines to present Premium Economy Each & every tips of your post are awesome. Thanks a lot for sharing. Keep blogging.if you any problem you can connect experts teams.expert team solves your problem in quick time.VIRGING CUSTOMER SERVICE

You share a awesome information…Get all the support you need for your Avast products. Well, help you ... Avast Support Number Security Premium for Android. Avast toll-free number ... Avast Tech Support Number.. avast customer care. http://avast-avast.comAvast customer support numberAvast support Number

I appreciate your post, Please Keep posting with more information…Get all-round system protection at norton.com/setup. Download the Norton setup, install it, and then activate it on www.norton.com/setup.http://nortoncomnortonnorton.com www.NorTon.com/setupNorton.com/setup

Thanks for sharing this useful information...Avail the benefits of Norton antivirus by visiting Norton.com/setup. For the installation and activation process, you can visit www.norton.com/setup. https://wwwnorton-norton.com/Norton setupwww.norton.com/setup

Traveling is fun itself, but when you get a chance to save money on air-tickets, the happiness part becomes double because saving on tickets means more money to does different adventure during the trip. Connect with our experts at the British Contact Number and get amazing discounts and deals that will put a smile on your face.

Leave all these worries on our experts and focus on the fun part of your trip. Get a solution of every flight and airlines related problems at one place, just call at Japan Contact Number and get instant solution for your problems. Our team of experts has experience of years in this field and with the help of the latest tools; they can provide you fast and reliable service.

Booking made by calling us has a whole lot of benefits. You’ll be treated as our special guests and offered a wide range of discounts to make you visit us again and forever. We love to spoil our customers with our cheap flight tickets and great flight assistance. Let’s have a look at the booking process when you call at Air France Contact Number.

PSl 2020 is nearly to coming in pakistan in February 20. The most awaited and the Popuplar event that is gonna be start. So Get ready and enjoy all the pakistan super laegaue live streaming, schedule, fixture and the other teams details. You can watch all the match updates and the Online ball by ball updates.

AWseome content , Great learning from your post. I am regular user of your blogs. Youyr post ARe too Informative. Please Kep Postinmg it.I am a web developer, and software engineer currently living in United States. My interests range from entrepreneurship to technology. I am having an experience of more than 6 years in field of Information Technology. i write Blog on technology and we provide service for softwares including antivirus.My Sites- mcafee.com/activatenorton.com/setupnorton.com/setup

What will make you feel like heaven on this earth? Having an elegant, gorgeous looking Bangalore Escorts in your arms is going to fulfil all your dreams. I am Kiran Bajaj, a 22-year-old Bangalore call girl in the prime of my life. Bangalore is a striking and awe-inspiring city in the world’s map. In fact, I am a great way to relax and unwind after a taxing and stressful day. And with me at your side, making this dream a reality is not at all any hassle. I am a charming, classy, and physically as well as intellectually stimulating Bangalore Escorts Service. Surely, I am going to charm and captivate you with incredible pleasures, that are just not limited to the flesh. I always go out of my way to make sure that you receive an extremely rewarding experience in my company. I offer excellent companionship services and you’re sure to get unforgettable moments in my company. Being an elegant Bangalore Call Girl, I always portray quality etiquettes. I am well-versed in a wide range of topics. I am a classy babe and you can effortlessly book me for delightful and interesting time. I am cent percent clients focused and make it a point that I offer the companionship you desire and crave for. Besides the erotic and sensual pleasures that are immensely gratifying and pleasing, I always lend a listening ears to your problems and offer workable suggestions.

Your blog is valuable us with significant information flight booking at,your new travel booking associate. Contact our pros. It was the key bearers to show Premium Economy Each and each tip of your post are astonishing. Much refreshing for sharing. Keep blogging.if you any issue you can interface authorities groups master bunch best deals.Frontier Phone NumberFrontier Phone NumberFrontier Phone Number.

Excellent information providing by your Article, thank you for taking the time to share with us such a nice article. Amazing insight you have on this, it's nice to find a website that details so much information about different artists. Kindly visit the EssayCorp website, we providing assignment help adelaide at best prices ever.

Still searching for best deals, offers, and packages on different sites? We are happy to inform you that your search ends here. By visiting Lufthansa Airlines Official Site you will have access to different deals and packages.

You can get it from avg to protect your identity. Browsers also contain cookies which track user’ location, id, and much other information and can be harmful so that AVG AntiTrack can protect you. For some devices, during installation, AVG AntiTrack may show SQL Error, which cannot let you use the application and so we have discussed the blog here.install avg with license numberAVG antivirus is the security program that works after it’s activation with avg retail. It requires an activation product key to activate AVG’s working and to protect your operating system. www.avg.com/retail | avg.com/retailavg download

The best WordPress hosting services are the ones with the best offer on their price, speed and customer service. Each of these elements is important as it makes a significant difference in the overall appeal of the service providers. as many WordPress hosting services can fall down due to their lack of management in one or more elements. The Best WordPress Hosting and Impact of Price and check here https://uzairch.comThe best WordPress hosting services are the ones with the best offer on their price, speed and customer service. Each of these elements is important as it makes a significant difference in the overall appeal of the service providers. as many WordPress hosting services can fall down due to their lack of management in one or more elements.

AVG Antivirus is one of those free tools that do the work others do for a lot of money. AVG look for viruses in your PC, eliminate them and quarantine the files, but it includes more features to be customized by you.www.avg.com/retail |avg.com/retail

Also check Canvas canine.After finding success with the Food and Travel blog, it was time to move onto Canvas Canine. With its new title Canvas Canine really lives up to its name, as it will keep you entertained and involved throughout its duration.

Thanks for a very interesting blog. What else may I get that kind of info written in such a perfect approach? I’ve a undertaking that I am simply now operating on, and I have been at the look out for such info. Satta king

Recuva 2020 Cracked is free windows utility software which has a quick scan for fast data recovery you can also enable a deep scan. A quick scan takes a small amount of time while in deep scan takes much longer. While in both modes the process remains smooth .and the PC remains stable. Hence, this app gives you a chance to recover deleted files which were deleted by mistake, pc crashes or with virus attack by this free recovery tool. It is easy to use and perfect to utilize and recovers a file that was removed from recycle bin.Is Created For Recovering The Losten DAta For Your Computer Is Some Cases It Has the Ability To Restore The Partition OF The Computer. Recuva Pro Crack 2019 Will Allows You To Make Your Data Back In Any Condition Like Attack Of Ransomware Also.

thanks for sharing this information with us. I am just surfing on internet and suddenly found this blog. Very Nice blog. Please have a look on my blog which is based on travel delta airlines phone number

Norton 360 Premium for up to 10 gadgets gives you ground-breaking layers of security for your associated gadgets and online protection. norton.com/setup Your own gadgets and data have assurance as you bank, shop, and post on the web, both at home and on open Wi-Fi.

Struggling with any type of QuickBooks query? Resolve it by eminent guidance of QuickBooks Poadvisor from QuickBooks Support Phone Number 1-833-780-0086. for more visit: https://g.page/qb-support-number-hawaii

Frozen 2 is an Adventure animated movie. It is a sequel film. before Frozen 2 its part 1 released on 22 November 2013. Title of part one "Frozen". This film is Directed by Chris Buck and Jennifer Lee and produced by Peter Del Vecho.

Looking for suryavanshi movie download 2020 to download or Sooryavanshi full movie watch online. Then stay with this page, you will find lots of information related to suryavanshi movie download mp4.

We will know some information about baaghi 3 full hd movie download 123mkv and a guide on how to download Baaghi 3 full movie or how to watch baaghi 3 full movie watch online. Tiger Shroff and Shraddha Kapoor's new movie Baaghi 3.

Looking for Hunt for the Wilderpeople movie to watch online or looking for Hunt for the Wilderpeople to download. Then you're landed on the right web page. In this post, I gonna give you a small review and more detail on how to watch Hunt for the Wilderpeople 2016 full movie online. So keep reading this post until the end.

The Hunt is an Action, Horror, Thriller English movie. Are you looking for the hunt full hd movie download? or The Hunt movie watch online free. Then you are landed on the right page. In this post, I will give you a lot of information about The Hunt movie 2020. And a guide on how to watch the hunt movie online.

Qatar Airways Official Site is made to provide the cheapest air tickets and resolve all the queries and problems that our customers might have during their journey via Qatar Airways flights. They can be anything regarding flights and airlines such as booking process, refunds or cancellations, in-flight entertainment, food and drinks, cabin class, etc.

Come of our Air Canada Airlines Official Site. Loaded with amazing features and functions, visiting our site has advantages and benefits that are unparalleled. Whether you are a economy, business or first class passenger with Air Canada Airlines, our well-tuned deals and packages make it sure that you travel with affordability.

QuickBooks is an advanced accounting application, still in many instances occurs with technical faults. For resolution of such issues, dial QuickBooks Customer Service Number 1-833-780-0086. Here, you will connect with Highly skilled professionals who provide Customer oriented results. For More Visit: https://g.page/quickbooks-support-california

The error code causes hindrances to the software functionality. This affects the work-flow of every organisation. For such errors give a call on QuickBooks Customer Support Number 1-833-780-0086. Don’t try to indulge in resolving on your own. For More Visit: https://g.page/quickbookssupporttexas

Thanks for posting this info. I just want to let you know that. Thank You So Much. I was checking continuously this blog and I’m impressed! Extremely helpful info particularly. I hope more from you. I was looking for this certain information. :) Thank you for sharing this valuable content. Two popular posts on my blog....Looking for Watch Avengers Endgame Online Free? Then continue this post, in this post, you will know much information related to Avengers: Endgame movie. And a guide on how you can watch Avengers endgame google drive movie from staying home...Toy Story 4 is an animation, adventure, comedy movie and this is an American movie. This movie was directed by Josh Cooley and produced by Mark Nielsen and Jonas Rivera and distributed by Walt Disney Studios Motion Pictures. It was released theatrically on June 21, 2019.Google Drive Toy Story 4... for Extraction 2020 full movie download, then you are in the right way. On this page, you will find a guide on how to watch Extraction full movie online free or Extraction Google Docs Download link HD.... I was looking for this. :)

Suffering with the technical snag of QuickBooks? Don’t worry, ring us on QuickBooks Enterprise Support Phone Number 1-833-780-0086. Our highly experienced & learned experts are available round the clock to offer assistance.

Traveling is the best thing to relax your mind & soul. It does not matter if you do traveling as a professional, businessman, or for fun. The major thing that can affect your traveling cost is cheap flights. Check out the following links to get the best deals & offers for flights and vacations anywhere in the world.

If confronting any sort of technical glitch in the software. Resolve it by calling on QuickBooks Customer Service Phone Number 1-833-780-0086. Our learned & Experienced QuickBooks professionals are always presented to offer technical help. For More Visit: https://g.page/quickbooks-support-california

Nice BlogQuickBooks Payroll is a widely used accounting software that is intended for the business of small as well as large sizes. From among other QuickBooks editions, this one is the best. Call QuickBooks Payroll Support Phone Number at 1-855-6OO-4O6O.